RE: CMP BF109F BUILDING THREAD
 

10 servos, most of which are idling for the vast majority of the flight. My Ki-61 has about the same number of servos (actually more because I have two for a bomb drop and a servo actuated canopy) and it only uses about 250 mah per flight on a 2000 mah 6V pack. No doubt, a 6V battery will discharge a bit faster than a 4.8V, so you need some extra when using 5 cells but I am certain I will get 5 or 6 flights easy with a 2000mah 6V battery with the servos I am using (two digitals, the rest standard). I think it would be a waste to use digitals on the flaps, throttle, and retract servos. The most you need on this plane would be 4. I would never push someone away from being "safe" though, so if you think you need more capacity, use it.

As for using 6V, I have never had a servo that had a problem with it, even standards like a Futaba S3004. I have seen cases where other people have had some "chatter." One advantage of a 6V pack is that you get to use the entire rated capacity. Since the low voltage level is still plenty for the reciever the battery has to be very low to cause a problem. A 4.8V battery cannot use it's entire capaciity because the low end of the voltage range is too low to operate the receiver safely.

RE: CMP BF109F BUILDING THREAD
 

Thanks Kahloq and Hot Rod Todd.

You really helped me out here. I'm gathering all the parts to put in the plane. Waiting for the Seirra retracts. I was one of the lucky guys, thanks to Kahloq.

Regards,

Eric Schumacher, Netherlands.

RE: CMP BF109F BUILDING THREAD
 

THere are a fair few futaba servos that don't work at 6v.

Rather than buying 1 R/X pack at 4000mah, you are much better off using 2 2000mah packs. Most of the warbird guys i fly with (myself included) use 2 r/x packs for redundancy. in fact in australia, you must have dual r/x packs if your model requires a Heavy model inspection. not that this 109 is going to be that heavy, but the number one killer of R/C models, after their owners:D are r/x packs and r/x switches. well worth having.

I'm still sitting here waiting for my lower cowl and rudder that were not in the box when i received this model to arrive[:@]:([:@].

thanks

dave

RE: CMP BF109F BUILDING THREAD
 

Depending on the plane size, I have used two batteries in parallel for the rx. BTW, I do not recommend using a digital servo on your throttle when setting up a glow plane. Ive had more then one burn up on the throttle channel almost causing the lost of the planes they were in. Somethign to do with their "desire" to constantly self-center themselves and being held a certain location(liek soemwhere in the throttle range) for extended periods of time.

RE: CMP BF109F BUILDING THREAD
 

Here's my latest mod, the tailwheel. I used a 1.20 size wheel from Hobby King that cost $5.95. I had to cut the mounting arm and mounted it to the stock tailwheel mount. Here is a photo of the wheel and one with it in place (not yet glued in). I think it looks pretty scale, a good wheel for the price.

RE: CMP BF109F BUILDING THREAD
 

That looks really great !

RE: CMP BF109F BUILDING THREAD
 

Hi

Just a note.

I began to link up my elevators with the CMP hardware. After a minor stress test on the CMP linkage to elevators, as i suspected with this type of connection, the configuration yields a lot of play.

The arrow shaft is very thin walled and not stiff, mine already split at one end.. Clevises already snapped as i tried to connect one to the horn. The "Y" connection is ok on short wire spans, but here for me, not good.

Do your own test and see if this is a real concern.

Imagine the loads with the large engines and a aprox 13-14lbs model.

I am going use a carbon rod to an internal linkage joining the 2 elevators, with the carbon rod pushing on center of the elevator load via an internal arm. No flex, no play.

Or i may use the CMP arrow shaft with a wood dowel that I can epoxy into it for additional stiffness making the hollow shaft solid instead of using up my carbon rods..

Steve

RE: CMP BF109F BUILDING THREAD
 

What I did for the elevator halves was, I used the black arrow shafts provided in the kit as guide tubes and ran 4-40 rods(with their respective grey plastic guide tubes inside the black arrow shafts) to the control horns. I am using two servos, one per elevator half. There is no slop at all this way. The black arrow shaft tubes basically prevent the 4-40 rods from bending. So, what you do is get the correct length you want and cut the black tubes down some. Then, place the grey plastic guide tubes from the 4-40 package inside the black tubes and glue them. You then simply run the 4-40 rods through the grey guide tubes and all is well.

RE: CMP BF109F BUILDING THREAD
 

Hey, Hot Rod Todd.

Could you post a link to the site where you found that WAY COOL tail wheel setup for us ?

Thanks, Don

RE: CMP BF109F BUILDING THREAD
 

I have a CMP Hellcat with the same set up, and the elevator likes to move around due to the weak linkage caused by the Y rod. At the very least you will have to connect the elevator halves with a torque rod. If you even use the shafts, I would stiffen them with carbon fiber glued in (6mm fits right inside the tube) and use 4-40 rods on the ends. On top of that you may need some guides to prevent it from flexing. I would also epoxy the rods into the arrow shafts, don't rely on the set screws alone to hold them. Seems like overkill, but this plane will fly very fast with any of the engines in the power range so a tight linkage will be necessary to prevent flutter.

RE: CMP BF109F BUILDING THREAD
 

Here's the link where I bought the tailwheel. Awsome place to get motors, speed controls, and batteries. It is shipped straight from China though, so you need a big enough order to minimize the shipping. Check out the 1:6 scale pilots too, they actually look pretty good for the price. Same basic wheel is available from Dubro for $14.69 at Tower.

[link=http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4671&Product_Name=Tail_W heel_System._w/_Steering_&_Spring_60-120_Size]Hobby King[/link]

RE: CMP BF109F BUILDING THREAD
 

I decided to put both cmp glass rods on the internal elevator control linkage. Basically like a pull pull system but with glass rods, so each rod splits the load with the other and also eliminate all play, yet will also work independent of the other in case one rod fails . No exposed linkage. Both rods connect to the same metal gear heavy duty servo.



Steve

RE: CMP BF109F BUILDING THREAD
 

why do manufacturers always use this system compared to Goldnrods or such much more secure

RE: CMP BF109F BUILDING THREAD
 

Steve,
Some questions if you don't mind.
1. How do the control horns attach to the wheel collars mounted on the rod that connects the 2 elevator surfaces together?
2. Are both horns attached to the same wheel collar, or are there 2 collars?
3. Why have you cut the fuselage apart at the lower back, and removed the post?
4. Do you plan a retract mechanism for the tailwheel?
5. How did you get the connecting rod past the inboard hinges without cutting the hinges?
Bob Q.

RE: CMP BF109F BUILDING THREAD
 

Cause they are cheap.

Its from China. They are going to cut costs and make things as cheap as possible to get the highest profit possible.

RE: CMP BF109F BUILDING THREAD
 

Hi Bob

Hope all is well.

1) The wheel collars are the cmp ones threaded for a 8-32 pan head screw, thread locked with a plastic clevis connector on it. If you have a questions on this part, let me know and I'll post a pic of the part.

2) two collars attached on opposing ground in flat spots on the piano wire rod.

3) CMP has put a nice radius on the rudder, I am going to take advantage of that by setting a new rudder post inward a bit and create the faired look as the elevators/ailerons have . And the rudder will fit better to the vstab top part.

4)No functioning tail wheel on this one, next one maybe. Most scale 109 locked tail wheels down.

5) Eliminated inboard hinge. The elevator control rod works as the inboard hinge. The CMP hinges will fail before this control rod ever fails.

Oh, I decided to wrap kevlar thread around the ends of the glass arrow shafts to reinforce the ends a bit so they don't split. Don't have to use kevlar, glass tape would work as well.


So how far along are you on yours Bob.

Steve

RE: CMP BF109F BUILDING THREAD
 

The servo end of the elevator linkage.

CA glue can bond to polyester resin well, but I integrated the ply to the factory wood and may put a bead of silicone to hold it in place if it does come loose somehow it will give me some control..


So am i adding weight, yes, but I am going to link all my flaps to one metal servo and save..

Too many servo behind the CG, not good.

Steve

RE: CMP BF109F BUILDING THREAD
 

Hi Steve,
I'm fine, the only problem is that when you're retired, the wife has a to-do list a mile long and working on the BF109 is way down at the bottom of the list.
My aluninum stock finally arrived and I managed to get one strut done and the 2 MG15's. I still need to drill the vent holes in th barrel cover.
I came across an interesting drawing of the tailwheel retract mechanism. It doesn't retract in the conventional manor. The strut is positioned at the forward end of the well. Slightly forward of the strut and slightly above the skin is a boss welded to the strut and attached to the strut through the boss to a bracket mounted to the skin forming mthe pivot point of the tailwheel. An actuator pivots the strut counterclockwise causing the wheel to pivot into the opening. This should be easy to duplicate. The first thing that comes to mind is a 90 degree bellcrank to an actuator y'd to the retract servo. If need be put the tailwheel on it's own channel which is slaved to the retract servo. This way you can set separate end points. thats about all the gems ive cone up with lately. Oh yes thanks for the picture of the elevator pushrods.
Bob

RE: CMP BF109F BUILDING THREAD
 

Bob,

I spent a few hours online last night looking for a schematic of the tailwheel retract mechanism too but couldn't find anything worthwhile. Is there any way you can post a picture of what you found? The mechanism for this plane seems a lot simpler and easier to duplicate than the retract on a FW-190.

Tim

RE: CMP BF109F BUILDING THREAD
 

Hi Bob. No problem. please don't hesitate with questions or suggestions.

I know what you mean about time. I have a wife, kids and I'm not retired. But we all need to diffuse in one way or another.

Important note on elevator control modification i did.

If anyone decides to do the hidden elevator control like I've shown, the bolts in the collects that control the elevator wire should be at 1 o'clock and 5 o"clock positions (angled forward away from the rudder post) so when they are pushed back the screws don't hit the rudder post and limit the elevator throws.

Steve

RE: CMP BF109F BUILDING THREAD
 

Tim,
It's easier to give you the address for the retract schematic. It appears to be from a Japanesse Magazine. Haven't had time to do a layout of the model mechanism to see what works.

Steve,
Thanks for the picture of the control arm, it cleared up things quite abit.
Bob




http://www.flickr.com/photos/farinih...7604022764260/

RE: CMP BF109F BUILDING THREAD
 

I have to give you guys credit for pushing the scale envelope to the extent that you mount a scale type retractable tail wheel in this plane. With the long tail any weight back there will likely make a need for some nose weight. I'm doing a few things here and there, but the not so large wing on this fairly large plane is keeping me in check a bit.

I got my Sierra retracts last night, and they look great! I can't wait to get them mounted and see how they look. Thanks Darrel!

I also got the OS 1.60 mounted. As mentioned earlier, the aluminum backed spinner I got from Dave Platt is a little smaller than the cowl, but I don't think it looks too bad mounted up. Here is a photo. I'm still working on the spinner nut, so the cone is just stuck on.

RE: CMP BF109F BUILDING THREAD
 

I sure hope someone get this baby airborne this weekend, I can't wait to see pics and get the flight report. [8D]

RE: CMP BF109F BUILDING THREAD
 

Is the Dave Platt spinner listed as a standard product?
I could not find a reference to it on his website.

Thanks,
Helge.

RE: CMP BF109F BUILDING THREAD
 

HW50

I noticed many methods of contact on the Platt web site.





You could ask D. Platt directly about the spinner. via email.

steve